JPS62189292A - Pawl for drill head of earth auger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pawl attached to the head of an earth auger trill, and more particularly to a pawl shape that takes wear resistance into consideration.

(Prior Art) Fig. 1 shows a conventional earth auger drill head with claws IA and IB, in which two screw plates 3A and 3B are welded to the head shaft 2, and these screw plates 3A
, 3B, one or more (two in the illustrated example) claws IA, IB are welded to the lower ends of each of the claws IA and IB arranged in the inner and outer directions. As shown in FIGS. 2 and 3, these claws IA and IB have a prismatic shape and are made by overlaying or brazing cemented carbide on the sharply formed tip 1a and outer surface ib. , and the tip 1a has an inclined surface 1c so that the width gradually becomes smaller.
It is formed.

In such a conventional structure, as shown in Fig. 3,
Since the tip of the outer claw IA protrudes outward from the rotation locus 4 of the outer surface 1b as the drill rotates, as shown in FIG. As shown in the shaded area 5, it wears out in a triangular shape.
Every 2 to 3 months, the head must be carried from the field to the factory, the old pawl IA must be cut off from the screw plates 3A and 3B, and the new pawl IA must be welded to the screw plates 3A and 3B. There are problems in that it requires frequent replacement and is uneconomical because it is expensive and uses a large amount of cemented carbide.

Therefore, as shown in FIG.
have already developed and proposed a shape in which both the inner and outer surfaces or the outer surface are formed into an arc shape along the rotation locus 4 shown in Fig. 4 (Utility Application No. 59-2813).
issue). With this shape, as the usage period passes, the claw 6A will wear from the outer surface 6a, and the degree of wear of the tip 6b, which plays the role of biting during hole drilling, will decrease, reducing the wear. Experiments have shown that when this structure is adopted, the lifespan can be extended by about four times compared to conventional methods.

(Problems to be Solved by the Invention) However, in the case of a claw with this structure, in which the inner and outer surfaces are simply formed in an arc shape, it is difficult to see the bottom surface of the excavated hole in the actually installed state, that is, as shown in FIG. When welded to the lower end of the screw plate 3A (3B) so as to be inclined with respect to 7, as shown in FIG. As a result, the tip of the claw digs into the bottom of the excavation hole from the outside, and although it is not as far as the conventional claw, the tip of the claw still A phenomenon occurred in which the parts wore out from the outside. In addition, when the claw 6 is attached to the screw plate, as shown in FIG.
The upper part 6e on the tip side of the claw protrudes further outward than the lower side, resulting in a problem that the outer upper part of the tip part 6a of the claw tends to wear out.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned points, and the present invention has been made in view of the above-mentioned points, and the shape of the pawl is changed from the outer surface of the pawl to the rotation of the drill. It is characterized by being formed in an arc shape along the rotation locus accompanying the rotation, and the tip of the claw is formed into a sharp point, or the claw is attached in a twisted shape so that it is horizontal in the state. .

(Example) As shown in the example diagram in FIG. 8, the claw of the present invention has a rectangular cross section when manufactured, for example, by forging (the claw of the present invention can also be manufactured by casting in addition to forging). The material is not simply bent into an arc shape along the side surface 7A of the excavated hole, but is also twisted so that the inner side 8b of the tip 8a of the claw 8, which is formed into a sharp point, is slightly downward. As shown in FIG.
When attached by welding to the lower end of the claw 8, the tip 8a of the claw 8 becomes horizontal.

With such a structure, the tip 8a of the claw 8 can be completely inserted into the bottom surface 7 of the excavated hole, and wear will not be concentrated on the outside of the tip 8a, and further,
In the mounting state, both the outer surface 8C and the inner surface 8d are vertical over the entire length, so the entire outer surface comes into contact with the wall surface 7A of the excavation hole. It is also possible to prevent this phenomenon from occurring. According to experiments, compared to conventional nails, 10-2
It was possible to maintain 0 times the lifespan.

FIG. 1O shows another embodiment of the present invention, in which the distal end 9A of the claw 9 is twisted from the intermediate portion so that the distal end 9a is horizontal when attached. In addition, the claw may be attached in a twisted shape on the end side, or three or more discontinuous surfaces may be formed on the upper and lower surfaces of the claw to form a twist as a whole. In addition, as shown in FIG. 11, a reinforcing plate 10 is provided on the back side of the screw plate 3A (3B).
Weld the reinforcing plate 10 and the screw plate 3A (3B).
It is also possible to weld the claws 11 to the parts. Further, as a means for attaching the claws to the screw plates 3A < 3B), bolting can be used in addition to welding and brazing.

(Effects of the present invention) According to the present invention, it is possible to prevent uneven wear of the tips of the claws compared to claws that are simply formed in an arc shape, further extending the service life and increasing the frequency of replacement. can be significantly reduced, there is no wastage of materials, and an economical nail can be realized.

[Brief explanation of drawings]

Figure 1 is a front view showing the head with conventional claws attached, Figure 2
Figure 3 is a perspective view showing the outer claw, Figure 3 is a partial plan cross-sectional view of Figure 1, Figure 4 is a plan view illustrating the problems of the conventional nail, and Figure 5 is the first work of the present inventor. A perspective view showing the claw developed in
Figures 6 and 7 are a side view and a front view of the installation state of the claw, respectively, and Figure 8 (A
). (B) and (C) are a side view, a top view, and a front view showing an embodiment of the claw of the present invention, respectively, and FIG. 9 is a front view showing the claw of the embodiment in an installed state. FIG. 1O is a perspective view showing another embodiment of the invention, and FIG. 11 is a side view showing still another embodiment of the invention.

Claims (1)

[Claims] In the claw attached to the head of the earth auger drill, the shape of the claw is such that the outer surface of the claw forms an arc along the rotation trajectory accompanying the rotation of the drill, and the tip of the claw is formed to be sharp. A claw for a drill head of an earth auger, characterized in that the part is twisted so as to be horizontal when the claw is installed.